The present invention relates to computer peripheral equipment in general, and more particularly, to thermal ink jet printers and optical scanners.
Thermal ink jet print cartridges are extensively utilized in printers attached to personal computers and in fax machines. They are also sometimes referred to as xe2x80x9cpensxe2x80x9d and provide good quality print and fast dry time on a variety of print media including common papers. Thermal ink jet print cartridges enable non-contact printing of both color and black and white text, numbers and graphic images, eliminating printer failures due to friction wear and foreign body interference. Their self-contained design and direct printer interconnect allows for fast, simple replacement, while avoiding the necessity for ribbons, pumps, etc. Thermal ink jet print cartridges are relatively small and virtually silent in operation. They have relatively low power consumption and EMI emissions, and represent an inexpensive alternative to laser print cartridges.
A conventional thermal ink jet print cartridge has an injection molded plastic rectangular outer housing with suitable projections and/or notches for precision registration in a transversely reciprocating carriage of a printer. The plastic housing may include an ink reservoir or the print cartridge may be a so-called xe2x80x9coff axisxe2x80x9d print cartridge that has a stationary ink supply connected by a flexible hose to the moving print cartridge. A nozzle plate on the outside of the housing of the thermal ink jet print cartridge has a plurality of nozzle orifices. Underneath each orifice is a firing chamber or ink ejection cavity commonly fed from a plenum. Ink is expelled through each nozzle utilizing a corresponding resistor element which rapidly heats a minute quantity of ink in response to an energizing signal controlled by a microprocessor in the printer. The minute quantity of ink is boiled, creating a bubble that ejects an adjacent ink droplet out of an orifice to form a dot on the print media. When the bubble collapses, ink immediately refills the firing chamber from the plenum. By rapidly firing ink droplets from various nozzles in a controlled pattern, as the print cartridge reciprocates transversely and the paper advances longitudinally, alphanumeric characters and/or graphic images can be printed. Separate black ink and color ink thermal ink jet print cartridges are sometimes used in the same printer. The full spectrum of colors can be formed on the print media by using combinations of different colors of ink, for example cyan (C), magenta (M), yellow (Y) and black (K), according to well known techniques.
Optical scanners are commonly employed in facsimile machines to convert text and graphics into digital information that can be communicated, for example, over phone lines and wireless networks. Typically a facsimile machine includes a stationary light source and a stationary optical sensor that both extend across the width of the document feeding path. Text and graphics are scanned as a document is propelled longitudinally through the facsimile machine. More recently flat bed scanners have become popular peripheral devices used with personal computers. Typically a document is placed on, or automatically fed to, a large horizontal glass or transparent plastic platen. An optical scanning head or bar that extends across the entire width of the platen reciprocates longitudinally over the stationary document to generate a very high resolution digital image that is processed and stored in the personal computer.
U.S. Pat. No. 4,583,126 of Stoffel discloses a scanner incorporating a monolithic image read bar positioned above the paper path and an ink jet print bar positioned below the paper path to allow copying to be performed substantially simultaneously with the reading of an original document.
U.S. Pat. No. 5,980,010 of Stephenson discloses a printer that is attached over the LCD display of an electronic camera. A separate scanning head and a separate ink jet print head are mounted to opposite sides of a carriage so that the displayed image can be scanned and printed substantially simultaneously. There is no need to illuminate the image being scanned since the device relies upon the light emitted by the LCD display.
U.S. Pat. No. 5,289,208 of Haselby discloses a inkjet printer in which an optical sensor separate from the pens but mounted on the reciprocating carriage includes a quad photo-diode detector. The outputs of the detector are indicative of the horizontal positions of vertical test lines imaged on the detector in conjunction with horizontal alignment correction, as well as the vertical positions of horizontal test lines imaged on the detector in conjunction with vertical alignment correction.
An ink jet printer has been commercialized that allows an optical scanner head to be swapped into the carriage for the pen. This is cumbersome and time consuming, especially since alignment must be performed after each device is snapped into the printer carriage. In addition, with this type of ink jet printer it is not possible to substantially simultaneously print and scan for purposes of making adjustments xe2x80x9con the flyxe2x80x9d to improve print quality.
It would be desirable to reduce the parts count, cost and complexity associated with optical document scanning by incorporating this capability into a thermal ink jet printer. It would also be desirable to monitor dot position, dot size and/or spectral information in a thermal ink jet printer in order to make corrections and improve print quality. At present thermal ink jet printers are commercially available that prompt the user to align a new cartridge upon insertion into the printer. This alignment involves a tedious process of printing rows of vertical test patterns and then having the user view the vertical test patterns. The user then clicks on response buttons on the personal computer screen corresponding to the printed test patterns that appear to be the most linear. The user must then confirm that a subsequently printed multi-color cross-shaped test pattern is acceptable.
It is therefore an object of the present invention to reduce the parts count, cost and complexity associated with optical document scanning by incorporating this capability into an otherwise conventional thermal ink jet printer.
It is another object of the present invention to provide a combination inkjet pen and optical scanner head that can be removably inserted into a reciprocating carriage in a document transport.
It is still another object of the present invention to monitor dot position, dot size and/or spectral information in a thermal ink jet printer in order to make corrections and improve print quality.
The present invention provides a combination ink jet pen and optical scanner head. A housing is configured for mounting on a carriage of a printer. A thermal ink jet print assembly is mounted in the housing for forming a plurality of ink dots on a print media adjacent to the housing. A light source is mounted in the housing for illuminating the print media adjacent to the housing. A sensor is mounted in the housing for receiving light reflected from the print media and generating electrical signals representative thereof.
The present invention also provides a method of improving print quality in a thermal ink jet printer by mounting a combination pen and optical scanner head on a carriage of a printer for reciprocation along a scan axis. A sheet of print media is propelled through the printer along a paper axis. A predetermined test pattern of dots of different ink colors is printed onto the print media using the combination pen and optical scanner head or another pen also mounted on the carriage. Predetermined dot position, dot size and/or spectral information is compiled by scanning the location, size and color of the dots of the test pattern using the combination pen and optical scanner head. Predetermined ink jet firing signals are corrected in accordance with pre-programmed parameters based on the compiled dot position, dot size and/or spectral information in order to improve print quality.
The present invention also provides a method of scanning a document with a pen for facsimile transmission or storage and printing with the same pen.
The present invention also allows a pre-printed media-type identifier, such as a bar code, to be read by a printer to determine if the media-type is compatible with the pen of a thermal ink jet printer.
The present invention also enables a method of determining the incremental paper advance distance through a thermal ink jet printer to allow for adjustments that optimally nest the print swaths.